The door readers are all-purpose access control devices, which check pre-defined means of identification with regard to their authorization and which deliver a control signal in order to open doors, gates or similar passage barriers. In contrast to access control devices at entries, passages and exits, they do not carry out any attendance control.

The typical application at doors is that the door will only be opened for authorized persons, i.e. with authorized means of identification. This could be, for example, the access to a car park, which is closed at night, but where the parking drivers are allowed to leave with their cars even out of normal opening hours. It could also be the entry to a car park, which, out of normal opening hours, is closed by means of a roller gate, but where season parkers are allowed to enter with their cars even out of normal opening hours. It could also be any door within a building, e.g. residential building, office building or hotel, which shall only be opened for certain customers.

There is a great variety of possible applications for door readers covering all requirements in which specific means of identification shall initiate certain actions by means of a trigger pulse.